KR101208768B1 - A method for manufacturing ceramic coating layer for improving corrosion resistance of metal and a thing having a ceramic coating layer thereof - Google Patents

Abstract

Ceramic coating layer manufacturing method for improving the corrosion resistance of the metal according to the present invention, a) preparing a metal substrate, b) heat-treating the ceramic powder at a constant temperature, and c) the ceramic powder on the surface of the metal substrate Depositing an aerosol deposition method to form a ceramic coating layer. The metal substrate is selected from magnesium or magnesium alloy, carbon steel, stainless steel, and the ceramic powder is selected from yttria stabilized zirconia (YSZ) and cerium oxide (CeO ₂ ). According to the present invention, the ceramic powder is deposited on the metal surface by using an aerosol deposition method to form a ceramic coating layer, and thus, corrosion resistance is very excellent.

Description

A method for manufacturing ceramic coating layer for improving corrosion resistance of metal and a thing having a ceramic coating layer according to the present invention.

The present invention relates to a method for manufacturing a ceramic coating layer, and more particularly, to improve the corrosion resistance of a metal, a ceramic coating layer for improving corrosion resistance of a metal, which forms a ceramic coating layer having excellent corrosion resistance on a metal surface by an aerosol deposition method. It relates to a manufacturing method and an article provided with a ceramic coating layer of the metal thereby.

Magnesium or magnesium alloys, aluminum or aluminum alloys, carbon steel and stainless steel are the most widely used metals in the modern industry. On the other hand, in order to apply these metals to actual products or special applications, it is required to increase the corrosion resistance by coating the surface thereof. Among various surface treatment methods, ceramic coatings having a higher corrosion resistance on these metal surfaces than metals are known to be very effective in improving the corrosion resistance of materials. Ceramic coating technology currently used for thin film coating includes chemical vapor deposition (CVD), physical vapor deposition (PVD), abrasion resistance of mechanical parts, and thermal spray coating, which are widely used in semiconductor and display fields. However, the coating layer by a thin film coating process such as CVD or PVD is not suitable for requiring a certain thickness or more for corrosion resistance when cracking or peeling phenomenon occurs when the thickness is several micrometers or more. On the other hand, the spraying process used for many corrosion-resistant coatings can be coated at a thickness of more than a few hundred micrometers at high speed, but there are problems such as pores, cracks, etc. of the coating layer is difficult to control the thickness and the surface is very rough.

On the other hand, as a ceramic coating technique which has been studied a lot recently, there is an aerosol deposition method. The aerosol deposition process is capable of high-speed coating, can form a dense and crack-free coating layer at room temperature, form a coating layer of a wide range of thickness, easy to control the composition and stoichiometric ratio of the coating layer, can use a variety of substrates Due to its advantages, it is being used and researched in various fields at high speed. In particular, since a dense ceramic coating is performed at room temperature, interest in research for improving corrosion resistance using metal as a substrate is increasing.

The present invention has been made in view of the above-mentioned, metal to form a ceramic coating layer excellent in corrosion resistance on the metal surface by aerosol deposition in order to improve the corrosion resistance of the metal, in particular magnesium, magnesium alloy, carbon steel, stainless steel It is an object of the present invention to provide a method for producing a ceramic coating layer for improving the corrosion resistance and thereby providing an article having a ceramic coating layer of metal.

Method for producing a ceramic coating layer of a metal using the aerosol deposition method according to the present invention, a) preparing a metal substrate; b) heat treating the ceramic powder at a constant temperature; And c) depositing the ceramic powder on the surface of the metal substrate by an aerosol deposition method to form a ceramic coating layer.

The ceramic powder is preferably any one of yttria stabilized zirconia (YSZ) and cerium oxide (CeO ₂ ).

The metal substrate is preferably any one of magnesium or magnesium alloy, carbon steel, stainless steel.

Heat treatment in step b) is preferably made for 1 to 5 hours within the range of 500 to 700 ℃.

Aerosol deposition in step c) is preferably deposited at a substrate transfer rate of 1 to 4mm / s.

The aerosol deposition in step c) is preferably made 2 to 5 times.

Aerosol deposition in step c) is preferably a gas supply at a flow rate of 10 to 30L / min.

On the other hand, the present invention provides a ceramic coating layer of the metal with improved corrosion resistance produced by the manufacturing method.

In addition, the present invention is an article having a ceramic coating layer of a metal formed by aerosol deposition of ceramic powder on the surface of the metal substrate, the metal substrate is selected from any one of magnesium or magnesium alloy, carbon steel, stainless steel, the ceramic The powder is selected from yttria stabilized zirconia (YSZ) and cerium oxide (CeO ₂ ), and the ceramic coating layer is deposited by the aerosol deposition method of any one of the powders to have a single structure.

According to the present invention, the ceramic powder is deposited on the surface of a metal substrate, in particular, magnesium or magnesium alloy, carbon steel, or stainless steel, which is widely used in industrial fields, to form a ceramic coating layer by aerosol deposition. . In addition, according to the present invention, by depositing yttria stabilized zirconia (YSZ) to form a coating layer, the ceramic powder has an effect of obtaining additional functions in addition to the corrosion resistance effect.

1 is a schematic diagram of an apparatus for aerosol deposition,
2 is an XRD analysis graph of the crystal phase of the coated magnesium alloy substrate according to Example 1 and Example 2 of the present invention,
3 is a photograph of the surface and the cross-section of the coating layer of the magnesium alloy surface according to Example 1 and Example 2 with a scanning electron microscope (SEM),
4 is a graph of the coincidence experiment results of Example 1 and Example 2,
5 is an XRD analysis graph of the crystal phase of the coated magnesium alloy substrate according to Example 3 and Example 4 of the present invention,
6 is a SEM photograph of the surface and cross section of Example 3 and Example 4,
7 is a graph of the coincidence experiment results of Example 3 and Example 4,
8 is a Nyquist graph of Examples 3 and 4,
9 is a Bode graph of Example 3 and Example 4,
10 is an XRD analysis graph of the crystal phase of a coated magnesium alloy substrate according to Example 5;
11 is a surface and cross-sectional SEM photograph of the coated magnesium alloy according to Example 5,
12 is a graph of the coincidence experiment results of Example 5,
13 is an XRD analysis graph of crystal phases of coated aluminum alloys according to Examples 6 and 7,
14 is a surface and cross-sectional SEM photograph of the coated aluminum alloy according to Example 6 and Example 7,
15 is a graph of the coincidence experiment results of Example 6 and Example 7,
16 is a Nyquist graph of Examples 6 and 7,
17 is an XRD analysis graph of the crystal phase of a coated carbon steel substrate according to Examples 8 and 9
18 is a graph of the coincidence experiment results of Example 8 and Example 9,
19 is a Nyquist graph of Examples 8 and 9. FIG.
20 is an XRD analysis graph of the crystal phase of a coated stainless steel substrate according to Example 10,
21 is a SEM image of the surface of the coated stainless steel substrate according to Example 10,
22 is a graph of the coincidence experiment results of Example 10,
23 is a Nyquist graph of Example 10. FIG.

The above objects, features and other advantages of the present invention will become more apparent by describing the preferred embodiments of the present invention in detail with reference to the accompanying drawings. Hereinafter, a method of manufacturing a ceramic coating layer for improving corrosion resistance of a metal and an article having a ceramic coating layer of the metal according to the present invention will be described in detail with reference to the accompanying drawings.

The method of manufacturing a ceramic coating layer according to the present invention comprises the steps of: a) preparing a metal substrate; b) heat treating the ceramic powder at a constant temperature; And c) depositing the ceramic powder on the surface of the metal substrate by an aerosol deposition method to form a ceramic coating layer.

The metal substrate is preferably selected from any one of magnesium or magnesium alloy, carbon steel, stainless steel. There are many kinds of metal substrates, and the present invention is not limited to a specific metal substrate type. However, the magnesium or magnesium alloy, carbon steel, and stainless steel are very widely used and widely used in industrial fields among metals, and need for corrosion resistance. Since this is especially required, it is used as a base material for forming the coating layer of the present invention.

B) As a pretreatment of aerosol deposition, the ceramic powder to be deposited is heat-treated at a predetermined temperature for a predetermined time. The purpose of the heat treatment is to remove moisture contained in the ceramic powder and to weaken the bond between the powders. There are various kinds of ceramic powders, but the ceramic powder applied to the present invention is selected from yttria stabilized zirconia (YSZ) and cerium oxide (CeO ₂ ). In addition to improving corrosion resistance, the YSZ and CeO ₂ have advantages in that the material itself has very good properties, economics, and various applications to various industries.

Although there may be differences depending on the type of ceramic powder, the general heat treatment conditions may be effectively performed by the heat treatment for 1 to 5 hours in the range of 500 to 700 ° C. Below 500 ° C., water is contained in the powder. Above 700 ° C., water is easily removed but causes agglomeration of the powder. In addition, in the treatment time of less than 1 hour, the moisture can not be sufficiently removed, the moisture is effectively removed at 5 hours or more, but the deposition is not performed properly due to the aggregation of the powder.

Next, c) looks at the step of forming a ceramic coating layer on the surface of the metal substrate by aerosol deposition of the ceramic powder.

1 shows a schematic of an apparatus for aerosol deposition. Carrier gas (He) is introduced into the aerosol chamber containing ceramic powder through the flow control device (MFC) and is deposited in a vacuum deposition chamber (Deposition Chamber) containing fine ceramic powders floating in the aerosol chamber It is sprayed through a nozzle to a substrate in the substrate. The substrate is mounted on the X-Y-Z stage or positioner to move in the X and Y axes by the movement of the stage. In the deposition chamber, the degree of vacuum is controlled by a mechanical booster pump. A clear explanation for the mechanism of forming the coating layer by aerosol deposition has not yet been made. However, in the light of various studies, the ceramic coating by aerosol deposition impinges on the substrate and the particles are sprayed onto the substrate. As it is crushed, some of the pieces are embedded in the substrate or make strong bonds with the existing deposited powder, the next particles collide behind them, and the collided particles are pulverized to form a strong bond layer, forming a coating layer. On the other hand, the aerosol in which the ceramic powder is deposited is different from the aerosol in which the ultrafine particles having a diameter of several nm or less are suspended, and particles up to several tens of micrometers in diameter are carried in a gas. It is right to see it.

Aerosol deposition processes tend to have greater thickness unevenness compared to other thin film / thick film processes, especially for thin film processes. In order to form a coating layer having a high corrosion resistance on the metal surface according to the present invention, a certain thickness is required to obtain a somewhat stable characteristic. That is, when the thin film thickness is thin, the thickness nonuniformity is large, and if the surface irregularities are generated, the characteristics are likely to be poor. Therefore, in order to solve the thickness and thickness nonuniformity of the desired coating layer, the coating layer is formed by adjusting the substrate transfer speed and the number of coatings. In the case of applying a thin film, the conveyance speed of the substrate is relatively fast, and in the case of a thick film formation, the conveyance speed of the substrate is relatively slow. On the other hand, in the case of thin film formation, it is possible to obtain a desired thickness by increasing the number of coating. The thickness of the coating layer increases with the number of coatings. However, in some thickness or more, the adhesion decreases due to internal stress, so the number of coatings is adjusted in consideration of this. The thickness and thickness non-uniformity of the coating layer may vary slightly depending on the type of substrate and the type of spray powder, but according to a preferred embodiment of the present invention, the substrate feed rate (stage moving speed) is within a range of 1 to 4 mm / s. , The number of coating is preferably in the range of 2 to 5 times. The thickness uniformity of the coating layer is controlled by controlling the transfer speed of the substrate. In case of depositing thin film of 2 ~ 3 μm or less, thickness nonuniformity appears. This is solved to some extent, and the film feed rate was reduced when forming a thick film. The number of coatings is controlled according to the transfer speed of the substrate. If the transfer speed is high, the uniformity of the substrate is obtained, but the deposition frequency is increased because the deposition efficiency is low. In addition, when the substrate feed rate is lowered, the deposition efficiency is increased, thereby reducing the number of coatings.

On the other hand, the present invention is not limited to this, but it is preferable to form a coating layer by aerosol deposition using only one of the ceramic powders, that is, YSZ, CeO ₂ ceramic powder. If there are two or more phases (including base) of the coating layer or the metal base material, galvanic cells may be formed between the phases and cause corrosion. Thus, a single phase can be very effective. In general, since the ceramic layer has excellent corrosion resistance, corrosion may not occur well even in a heterogeneous form. However, when different heterogeneous phases are formed, compounds with high corrosion potentials or phases act as cathodes and compounds with low phases or cathodes act as anodes, which may cause potential differences between the coating layer and the base, which may accelerate corrosion of the base metal. .

On the other hand, other aerosol deposition conditions in the aerosol deposition is not particularly limited, the nozzle size is 10 to 50mm, the flow rate is 10 to 50L / min, the injection speed of the powder by the nozzle is 200 to 400m / s.

Hereinafter will be described in detail Examples and Experimental Examples of the present invention.

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Example 3 YSZ Deposition on Magnesium Alloy Substrates

Magnesium alloy substrate was used AZ31, YSZ was used as the coating raw material powder. As the deposition conditions, the nozzle size was 25 mm, 4 mm / s at the substrate transfer speed, and the flow rate was 30 L / min, and the coating was carried out by the aerosol deposition method. Such coating was performed four times.

Example 4 Deposition of YSZ on Magnesium Alloy Substrate

The coating layer was formed under the same conditions as in Example 3 except that the aerosol deposition conditions were 1 mm / s at the substrate transfer speed and the coating was performed three times.

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Example 8 Deposition of YSZ on Carbon Steel Substrate

20 C was used for the carbon steel substrate, and YSZ was used as the coating raw material powder. As the deposition conditions, the nozzle size was 25 mm, 1 mm / s at the substrate transfer speed, and the flow rate was 30 L / min, and the coating was carried out by the aerosol deposition method. Such coating was performed three times.

Example 9 Deposition of YSZ on Carbon Steel Substrate

The coating was carried out under the same deposition conditions and coating times as in Example 8 except that the carbon steel substrate was used at 45C.

Example 10 Deposition of YSZ on Stainless Steel Substrates

YSZ was used as coating raw material powder on the stainless steel substrate. As the deposition conditions, the nozzle size was 25 mm, 4 mm / s at the substrate transfer speed, and the flow rate was 30 L / min, and the coating was carried out by the aerosol deposition method. Such coating was performed four times.

Experimental Example 1 TiO ₂ Coated Magnesium Alloy

XRD  Pattern analysis, surface and cross section analysis

FIG. 2 shows the same magnesium alloy substrate (Uncoated AZ31) used in Example 1 (AD-TiO ₂ -2times) and Example 2 (AD-TiO ₂ -5times) and uncoated Example 1 and Example 2. FIG. The graph of the crystal phase analyzed by X-ray diffraction pattern (XRD) is shown. As shown in FIG. 2, the surface coating layer of the coated magnesium alloy is composed of a rutile TiO ₂ phase, and the TiO ₂ phase was clearly seen as the number of coatings increased.

Fig. 3 shows photographs of the surface (left) and the cross section (right) of the coating layer of the magnesium alloy surface according to Example 1 (upper view) and Example 2 (lower view) with a scanning electron microscope (SEM). The coating layer formed as shown showed a similar surface shape and showed a somewhat irregular shape. On the other hand, the cross-sectional observation of the coating layer showed a thickness of 2 ~ 8㎛ according to the number of coatings and it can be seen that the inside of the coating layer has a dense structure without cracks or holes. The density of the coating layer prevents contact with the atmosphere for preventing oxidation and oxygen in the solution or with ions (Cl-) causing corrosion, which in turn means that the corrosion resistance can be improved according to the embodiments.

Corrosion Resistance Characteristics

Various electrochemical corrosion experiments were conducted in 3.5 wt% brine to evaluate the corrosion resistance of coating samples. Brine at a concentration of 3.5 wt% represents a very harsh corrosive environment as a concentration of seawater.

4 is a coincidence experiment showing the change of current with voltage in 3.5 wt% salt water. Both specimens of Example 1 (AD-TiO ₂ 2times) and Example 2 (AD-TiO ₂ 5times) showed higher corrosion potential and lower current density than uncoated magnesium alloy base material (Uncoated AZ31). The calculated polarization resistance values indirectly confirmed improved corrosion characteristics compared to the base metal. Table 1 shows the polarization curve parameters and their numerical values related to the above-mentioned results.

Experimental Example 2-YSZ Coated Magnesium Alloy

XRD  Pattern analysis, surface and cross section analysis

FIG. 5 shows X-ray diffraction (XRD) of Example 3 and 4, YSZ raw powder and uncoated magnesium alloy substrate (uncoated AZ31) used in Examples 3 and 4 pattern) shows a graph. The coating layers of Examples 3 and 4 are formed of a ZrO ₂ phase having the same cubic structure as the raw powder.

FIG. 6 shows SEM photographs of the surface (top) and cross section (bottom) of Examples 3 and 4. FIG. It can be seen that a dense coating layer without cracks or holes is formed on and inside the coating layer. The coating layer thickness was 3 ~ 5㎛ depending on the coating conditions.

Corrosion Resistance Characteristics

FIG. 7 shows polarization curves of the coated magnesium alloys and the uncoated magnesium alloys (uncoated AZ31) according to Example 3 and Example 4 through coincidence experiments. Table 2 below shows the variables associated with the polarization curve. Both specimens of Examples 3 and 4 showed higher corrosion potentials and lower current densities than uncoated magnesium alloy base materials (Uncoated AZ31). The calculated polarization resistance values indirectly confirmed improved corrosion characteristics compared to the base metal. Table 2 shows the polarization curve parameters and their values related to the above-mentioned results.

In the data of the YSZ coated sample obtained in Example 4 shown in Table 2, the polarization resistance (Rp) of the coated sample was increased by about 10,000 times compared to the uncoated magnesium alloy (AZ31) and the current density (Icorr) by about 10,000 times. Decreased. In addition, it can be seen that the corrosion potential (Ecorr) also increases about 0.2V.

Impedance tests were conducted to investigate the corrosion characteristics of the base material / coating layer, the electrolyte solution / coating layer, and the coating layer. All impedance experiments were performed in 3.5 wt% aqueous brine (NaCl) solution and 30 minutes after soaking to obtain stable open circuit voltage. 8 is a Nyquist graph of an A Z31 magnesium alloy and an YSZ coated AZ31 magnesium alloy and an uncoated magnesium alloy (uncoated AZ31) according to Examples 3 and 4. FIG. The x-axis represents the real resistance (actual impedance) and the y-axis represents the virtual resistance (virtual impedance). The unit of the y-axis is resistance, but not measured as real resistance. The radius of the circle in the graph shows the corrosion resistance of the coating layer, and the larger the radius, the higher the corrosion resistance. The graph inserted in the Nyquist graph of Example 4 is a Nyquist graph of the magnesium alloy (AZ31) base material, and the actual resistance is 200 Ωcm 2 or less, whereas the coated specimens according to Examples 3 and 4 were 1-20 MΩcm 2. High seal resistance is shown. In general, in the case of the coating layer, the capacitance cannot be ideally measured due to the composition of the coating layer, the nonuniformity of the surface, the presence of defects, the size of the bond, the broken shape, and the like. That is, the resistance, capacitance, and impedance change non-ideally according to frequency in space-time, and the capacitance is expressed as a constant phase element (CPE). In general, one or more time constants appear depending on the structure and characteristics of the coating layer, which is represented by one time constant in the case of a single coating layer, the same structure and composition as the inside of the coating layer, and no defects in the interior and surface, that is, in the case of very dense coating layers. Although it is interpreted as an equivalent circuit having one resistance and capacitance, most ceramic coating layers have internal micro defects, and these defects become ion conductive paths according to frequency. In addition, the structure of the coating layer is changed by the reaction product occurring on the surface of the base material and the composition inside the coating layer during the corrosion process, and thus, one or more time constants exist.

Such changes can be seen in the Bode graph of impedance and FIG. 9 is a Bode graph of YSZ coated magnesium alloy samples and uncoated magnesium alloy samples according to Examples 3 and 4. It can be seen from the phase change with frequency that two or more time constants appear in the intermediate and high frequency regions of the coated specimen. Capacitance is calculated at the frequency at which the virtual impedance is at its maximum. The higher the resistance, the lower the capacitance. Phase changes with high impedance values and large angles and wide distributions indicate high resistance to corrosion of the coated sample. | Z | according to frequency The low frequency in the graph indicates that the sample impedance is derived from the resistance of the corrosion process and is directly related to the corrosion protection of the coating layer and refers to the polarization resistance of the coating layer. In the low frequency region of the YSZ coated sample, the impedance shows an impedance value of 10000 to 100000 times higher than that of the uncoated sample.

Experimental Example 3 Al ₂ O ₃ Coated Magnesium Alloy

XRD  Pattern analysis, surface and cross section analysis

FIG. 10 shows an X-ray diffraction pattern (XRD) graph of the coated magnesium alloy according to Example 5 and the same uncoated magnesium alloy (Uncoated AZ31) used in Example 5. FIG. The coating layer of Example 5 is formed in the α-Al ₂ O ₃ phase and the surface is somewhat rough and nonuniform.

FIG. 11 shows a SEM image of the surface (left) and cross section (right) of the coated magnesium alloy according to Example 5. FIG. The coating layer thickness was about 3 μm.

Corrosion Resistance Characteristics

FIG. 12 shows the polarization curves of the coated magnesium alloys and the uncoated magnesium alloys (Uncoated AZ31) according to Example 5 through a coincidence experiment, and Table 3 below shows the variables related to the polarization curves.

According to the results of the coincidence experiment, the Al ₂ O ₃ coated magnesium alloy sample showed lower corrosion current density and higher corrosion potential than the uncoated magnesium alloy, and showed the passivation behavior that corrosion does not occur well in the potential range above the corrosion potential. In addition, the low current density in the entire potential range means a low corrosion rate of the Al ₂ O ₃ coated sample. According to Table 3, the polarization resistance (Rp) of the coated specimen was about 1000 times higher than that of the uncoated specimen. . This means that the corrosion resistance of the magnesium alloy is greatly improved by the Al ₂ O ₃ coating layer formed on the surface.

Experimental Example 4-YSZ Coated Aluminum Alloy

XRD  Pattern analysis, surface and cross section analysis

FIG. 13 shows X-ray diffraction analysis (XRD) of YSZ coated aluminum alloys according to Examples 6 and 7 and the same aluminum alloys (uncoated AA1015, uncoated AA7075) used in uncoated Examples 6 and 7. X-ray diffraction pattern) The coating layers of Example 6 and Example 7 are formed of a ZrO ₂ phase of cubic crystal structure.

In FIG. 14, the upper part shows the surface (left) and the cross section (right) SEM photograph of the coated aluminum alloy according to Example 6, and the lower part is the surface (left) and the cross section (right) of the coated aluminum alloy according to Example 7. ) SEM pictures are shown. As shown in the surface picture, the surface of the coating layer shows the shape of the network structure. As shown in the cross-section picture, the YSZ coating layer was formed to have a thickness of about 5 μm regardless of the type of the aluminum alloy. It can be seen that it is a compact structure that can not identify the hole.

Corrosion Resistance Characteristics

FIG. 15 shows the polarization curves obtained from the coincidence experiments of the coated aluminum alloys according to Examples 6 and 7 immersed in 3.5 wt% NaCl solution.

For all coated aluminum alloys, the current density is significantly reduced compared to the uncoated specimens. However, the oxidation / reduction potential of the YSZ coated AA7075 aluminum according to Example 7 is about -0.94 V (vs. SCE) after coating, and the 0.4 V is improved, whereas the corrosion potential of the AA1015 aluminum alloy according to Example 6 is YSZ coated. Did not improve through. However, looking at the behavior of the cathodic reaction resulting from the hydrogen generation reaction coated specimens at -2.0 V (vs. SCE) as compared to the uncoated samples of about 10 ^-3 to ¹⁰ show a low value of ^4. This means that hydrogen generation on the surface of the aluminum alloy is greatly suppressed by the YSZ coating layer, and the reduction of the hydrogen evolution reaction reduces the effect of fracture which can be caused by the effect of hydrogen invading into the aluminum alloy and the surface defects caused by hydrogen generation. This results in ultimately improving the corrosion resistance properties of the aluminum alloy. The polarization resistances of the coated and uncoated aluminum alloys calculated through the polarization curve are shown in Table 4 below.

Through the various parameter values shown in Table 4, the corrosion reaction of aluminum alloy was greatly reduced by the surface YSZ coating layer. In particular, the polarization resistance of AA7075 aluminum alloy was very high, about 6 MΩcm ² . This means that the YSZ coating layer formed in the aerosol deposition method can effectively suppress the corrosion reaction of the aluminum alloy in the harsh corrosive environment.

FIG. 16 is a Nyquist graph of YSZ coated aluminum alloys and uncoated aluminum alloys (uncoated AA1050, AA7075) according to Examples 6 and 7 measured in salt water at seawater concentration. In the impedance graph, the coated AA7075 aluminum alloy exhibits typical CPE behavior and AA1050 aluminum is characterized by capacitance. The coated AA7075 sample also exhibits much higher real and virtual resistance than the coated AA1050 sample.

Experimental Example 5-YSZ Coated Carbon Steel>

XRD  Pattern analysis

FIG. 17 shows X-ray diffraction analysis (XRD: X−) of YSZ coated carbon steels according to Examples 8 and 9 and the same carbon steels (uncoated 20C, uncoated 45C) used in Examples 8 and 9 uncoated. ray diffraction pattern) The coating layers of Examples 8 and 9 were formed of a ZrO ₂ phase of cubic crystal structure.

Corrosion Resistance Characteristics

FIG. 18 shows the polarization curves obtained from the coincidence experiments of the coated carbon steels according to Examples 8 and 9 immersed in 3.5 wt% NaCl solution.

For all coated carbon steels the corrosion current density is shown to be lower than for the uncoated specimens. In particular, the corrosion current density of the YSZ coated 45C carbon steel according to Example 9 was reduced by more than 1000 times, indicating a low corrosion rate. However, the corrosion potential was lowered by about 0.4 V after coating, which is due to the fact that hydrogen generation on the carbon steel surface was largely suppressed by the dense YSZ coating layer on the 45C carbon steel surface. In the case of the YSZ coated 20C carbon steel according to Example 8, the corrosion potential did not change significantly and the corrosion current density was also slightly reduced compared to the uncoated carbon steel.

19 is a Nyquist graph of YSZ coated aluminum alloys and uncoated carbon steels (uncoated 20C, uncoated 45C) according to Examples 8 and 9, measured in salt water at seawater concentration. It can be seen that the corrosion resistance of the carbon steel after the YSZ coating is greatly improved. The YSZ coated 45C carbon steel according to Example 9 shows a high impedance resistance of 10 MΩcm 2 or more, which is consistent with the coincidence experiment. However, the impedance results of the YSZ-coated 20C carbon steel, which is different from those of Example 8, showed a significantly different phenomenon from that of the coincidence experiment. The impedance value of 20C carbon steel after YSZ coating was greatly improved due to the formation of dense YSZ film on the carbon steel surface.

Experimental Example 6-YSZ Coated Stainless Steel

XRD  Pattern analysis, surface analysis

FIG. 20 shows X-ray diffraction pattern (XRD) of YSZ coated stainless steel according to Example 10 and the same uncoated SUS used in uncoated Example 10. The graph is shown. The coating layer of Example 10 is formed of a ZrO 2 phase having a cubic crystal structure.

FIG. 21 shows a SEM image of the surface of YSZ coated stainless steel according to Example 10. The surface of the coating layer shows the shape of the network structure, it can be seen that the surface is a dense structure that can not identify cracks or holes.

Corrosion Resistance Characteristics

FIG. 22 shows the polarization curves obtained as a coincidence experiment of coated stainless steel according to Example 10 immersed in 3.5 wt% NaCl solution.

It can be seen that the YSZ coating on the stainless steel surface increases the corrosion potential of the substrate and reduces the corrosion rate.

FIG. 23 is a Nyquist graph of YSZ coated stainless steel according to Example 10 and uncoated SUS used in uncoated Example 10, measured in brine at seawater concentration. Although the graphs are similar in shape, the radius of the Nyquist plot has increased significantly since YSZ coating, indicating the high corrosion resistance of the coated stainless steel.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described specific embodiments. That is, those skilled in the art to which the present invention pertains can make many changes and modifications to the present invention without departing from the spirit and scope of the appended claims, and all such appropriate changes and modifications are possible. Equivalents should be considered to be within the scope of the present invention.

Claims (9)

delete delete delete a) preparing a metal substrate which is one of magnesium or magnesium alloy, carbon steel, stainless steel;
b) heat-treating the ceramic powder, which is any one of yttria stabilized zirconia (YSZ) and cerium oxide (CeO ₂ ), within a range of 500 to 700 ° C. for 1 to 5 hours; And
c) depositing the ceramic powder on the surface of the metal substrate by an aerosol deposition method to form a ceramic coating layer; Including,
The size of the nozzle by the aerosol deposition method is 10 ~ 50mm, the flow rate is 10 ~ 50L / min, the injection speed of the powder by the nozzle is characterized in that the corrosion resistance of the metal is characterized in that 200 ~ 400m / s Ceramic coating layer manufacturing method for.
The method of claim 4, wherein
Aerosol deposition in step c) is a ceramic coating layer manufacturing method for improving the corrosion resistance of the metal, characterized in that the deposition at a substrate transfer rate of 1 to 4mm / s.
The method of claim 4, wherein
Aerosol deposition in step c) is a ceramic coating layer for improving the corrosion resistance of the metal, characterized in that made 2 to 5 times.
The method of claim 4, wherein
Aerosol deposition in step c) is a ceramic coating layer for improving the corrosion resistance of the metal, characterized in that the gas is supplied at a flow rate of 10 to 30L / min.
An article provided with a ceramic coating layer of a metal produced by the method of claim 4.
As a ceramic coating layer structure of metal formed by aerosol deposition of ceramic powder on the surface of a metal substrate,
The metal substrate is selected from any one of magnesium or magnesium alloy, carbon steel, stainless steel,
The ceramic powder is selected from yttria stabilized zirconia (YSZ), cerium oxide (CeO ₂ ),
The ceramic coating layer is only one of the powders of the powder size of the nozzle by the aerosol deposition method is 10 ~ 50mm, the flow rate is 10 ~ 50L / min, the injection speed of the powder by the nozzle is 200 ~ 400m / an article with a ceramic coating layer of metal, characterized in that it is deposited and has a single phase.

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